The A Diminished chord is a three-note chord made up of A, C, and E♭. It is built from a root, minor third, and diminished fifth.
Construction
A Diminished = Root + Minor 3rd + Diminished 5th = A · C · E♭
| Note | Interval | Degree |
|---|---|---|
| A | Root | 1 |
| C | Minor 3rd | ♭3 |
| E♭ | Diminished 5th | ♭5 |
A Diminished Inversions
| Position | Notes |
|---|---|
| Root Position | A – C – E♭ |
| 1st Inversion | C – E♭ – A |
| 2nd Inversion | E♭ – A – C |
Key Signature
A Diminished chord is built from symmetrical or ambiguous intervals, so it doesn’t belong to a single key and has no key signature of its own.
A Diminished — Frequently Asked Questions
What is the A Diminished chord on piano?
The A Diminished chord contains the notes A – C – E♭. On piano, play these notes together to sound the chord.
What notes are in the A Diminished chord?
The A Diminished chord contains: A (root), C (minor third), and Eb (diminished fifth). Both intervals are compressed: the minor third is 3 semitones above the root, and the diminished fifth is 6 semitones — a tritone.
How does A Diminished differ from A Minor?
A Minor has a perfect fifth. A Diminished lowers the fifth by one semitone to Eb (diminished fifth). That extra compression creates intense harmonic tension — the tritone between root and diminished fifth is the most dissonant interval in Western music.
What is the symbol for the A Diminished?
A Diminished is written as Adim or A°. The ° or "dim" symbol means both the third and fifth are minor/diminished. Do not confuse with Adim7 or Aø (half-diminished), which include additional notes.
What are the inversions of A Diminished?
First inversion (A Diminished/C): C–Eb–A. Second inversion (A Diminished/Eb): Eb–A–C. Diminished triads are used in classical music as the vii° chord — the chord one semitone below the tonic, with strong resolution pull.
How is A Diminished used in music?
A Diminished most commonly functions as the vii° chord in a major key, creating strong resolution back to the tonic. It also works as a chromatic passing chord between two nearby chords, and in classical music as a brief point of dissonance. Jazz uses the full four-note dim7 more often than the triad.
What songs use diminished chords?
Michelle (Beatles) uses a diminished chord as a chromatic passing chord. Many classical pieces use vii°–I cadences. Jazz standards use dim7 chords as chromatic passing and approach chords. Diminished harmony also appears in flamenco and film music for dramatic tension.